REMOVAL OF INFLUENZA-A VIRUS, PHAGE T1, AND PP7 FROM FLUIDS WITH A NYLON 0.04-MU-M MEMBRANE-FILTER

We tested the ability of a 0.04-mum nylon membrane filter to remove vi ral agents (influenza A virus, 80-120 nm; phage T1, 50-150 nm; and pha ge PP7, 25 nm) from the following media: ultrapure water (UPW), Dulbec co's modified Eagle minimum essential medium (DMEM), gelatin phosphate (GP), DMEM with 10% (DMEM-10) fetal bovine serum (FBS), and 100% FBS. When challenged with at least 3.0 x 10(7) plaque-forming units/mL, no influenza A virus was detected downstream of the filter with any of t he fluids tested. The titer reduction (Tr) was determined using the eq uation: Tr = Concentration Input (PFU/mL)/Concentration Filtrate (PFU/ mL) Higher concentrations of phage Tl were removed from UPW (Tr = 1.6 x 10(6)) and DMEM (Tr = 1.1 x 10(6)) than from GP (Tr = 9.3 x 10(3)), DMEM-10 (Tr = 1.5 X 10(2)), and 100% FBS (Tr = 2.4 x 10(2)). Phage PP7 was removed in significant numbers only in ultrapure water (Tr = 8.5 x 10(4)). The results indicate that adsorption enhanced the titer redu ction in fluids containing low levels of protein. The titer reduction in DMEM-10 and 100% FBS may reflect the sieving properties of the 0.04 -mum filter. As expected, a much smaller Tr was observed in the filtra te of the 0.2-mum filters, compared to the 0.04 mum filters. In contra st to the 0.04-mum filter, no increase in Tr was detected when the 0.2 -mum filters were challenged with virus diluted in UPW compared with v irus diluted in GP. These results suggest that the 0.04-mum filter has greater adsorptive properties than the 0.2-mum filter. (C) 1994 by Jo hn Wiley & Sons, Inc.